A typical tour bus is a 40 foot long, 40,000 lbs GVWR over-the-road motor coach configured with one front door and row seating for about 50 people. The motor coach industry in the U.S. has approximately 44,000 buses and consumes almost 500 million gallons of fuel per year. The current practice is that while these buses are parked at loading or unloading terminals and in route stop-overs the HVAC for the driver and passengers is supplied by power-take-offs (PTOs) from the engine and, thus, require the engine to be running. However, it is undesirable to keep the engine of the vehicle running while it is parked for a variety of reasons such as, but not limited to, noise, exhaust emissions, fuel consumption, efficiency, wear and tear on the engine, and anti-idling laws.